Structural integrity assessment of corroded reinforced concrete slab-column connections

Said, Mahmoud Essam (2019) Structural integrity assessment of corroded reinforced concrete slab-column connections. Doctoral (PhD) thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (9MB)

Abstract

Reinforced concrete (RC) is widely used in structures, e.g. residential buildings, bridges, marine structures, and offshore structures. Some RC structures are constructed in harsh environmental conditions, which increase the probability of their deterioration. Corrosion is one of the main causes of deterioration in concrete structures. Consequently, further research is needed to better understand the effect of corrosion on different RC structural elements and materials. In this thesis, the punching shear behaviour of RC two-way slabs was investigated under different levels of corrosion. In addition, different corroded areas were also investigated. Accelerated corrosion techniques were used to achieve the targeted corrosion levels and areas. The objective of this study is to provide experimental information and assessments of the structural performance and behaviour of corroded RC two-way slabs under loading. The objectives were achieved by evaluating the effect of three different levels of corrosion on the punching shear of two-way RC slabs; mild corrosion (15% mass loss); moderate corrosion (25% mass loss); severe corrosion (50% mass loss). In addition, three different delaminated corroded areas will be considered: small corroded area; a large corroded area with enough reinforcement development length; large corroded area without enough reinforcement development length. The experimental program was designed based on statistical methodology in order to do a regression analysis at the end of the test period for the obtained results. The regression analysis used to construct predicted equations that calculate the residual carrying load capacity for corroded RC two-way slabs. The concrete mixture used to pour those elements was designed to conquer the exposure requirements for horizontal elements against de-icing agents according to ACI. For ensuring the poured concrete had an acceptable quality against chloride ions penetrations, rapid chloride penetration test and chloride diffusion were measured for standard cylinder specimens taken during the pouring. The corrosion performance was monitored for all tested slabs by measuring and tracking current measurement, corrosion cracks widths propagation, half-cell potential measurements, natural frequency measurements, chloride content measurements, and mass loss. In addition, the structural behaviour of the corroded slabs was evaluated based on cracking patterns, deflection capacities, deflection profiles, slab rotations, energy absorptions, and ductility indices. Moreover, the actual capacity for each corroded slab was compared with the predictions of punching capacities according to the yield line theory and four different: the Canadian Code (CSA 23.3-14), the American Code (ACI 318-11), the British Standard (BS 8110-97), and the European Code (EC2). Furthermore, this thesis showed a proposed technique to predict roughly the capacity of the different corroded area in the two-way reinforced concrete slabs using current codes. Finally, equations were proposed based on the analysis of variance for the experimental results that could be used by practicing engineers to determine the residual capacities for existing reinforced concrete two-way slabs suffer from corrosion. The experimental results will create a database for corroded slabs under real conditions. The database can then be used to verify future analytical studies of corroded RC structures. Thus, the thesis outcomes will help structural engineers to evaluate the strength degradation and load responses of such structures.

Actions (login required)

View Item